Glossary of common wooden boat design/construction terms

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Alpha

Apex - The lowest point in a cut rabbet where the inside face of a plank would end. In profile, it lies between the rabbit and bearding line. Sometimes called the middle line.

Apron - A structural backing piece fit behind the stem. Often wider than the stem and set to form the after part of the rabbet.

Ashcroft Construction - Double diagonal planking system with the planks of both skins raking in the same direction.

Athwartships - At right angles to the centerline plane of the hull.

Bravo

Backbone - The "spine" of the hull from which the frames radiate.

Back Rabbett - The surface against which the side of a plank lies in a rabbetted member. The end fastenings of the plank penetrate the back rabbett of a stem or sternpost; the lower or inner edge fastenings of a plank penetrate the back rabbett of a keel or horn timber. See diagram below.

Rabbett line = Outer Rabbett Line
Apex Line = Middle Rabbett Line, Margin Line 
Bearding Line = Back Rabbett Line, Inner Rabbet Line

Ballast - Added weight either within or external to the hull added to improve the stability of a vessel or bring it down to its designed lines.

Balsa Sandwich - End grain balsa wood used as a core between FRP laminates.

Bastard Sawn - Hardwood lumber in which the annual rings make angles of 30 degrees to 60 degrees with the surface of the piece.

Batten - A thin flexible piece of wood. Used to create a smooth, fair, line.

Beam - A structural member supporting a load applied transversely to it. The transverse members of a deck framing system; the width of a vessel.

Beam Knee - A gusset like member used to connect a beam to a frame.

Beam Mold - A pattern or template used for marking the shape or camber of deckbeams.

Bearding Line - The line formed by the intersection of the inside of the planking with the side or face of the keel.

Bed Logs (of centerboard case) - The structural members of the centerboard case that run fore and aft next to the center board slot.

Bending Steam - The process of forming a curved wood member by steaming or boiling the wood and bending it to a form.

Bilge Plank - A strengthening plank laid inside or outside of a vessel at the bilge's turn; also known as "Bilge Stringer".

Binding Strake - An extra thick strake of side or deck planking.

Box Section Mast - A hollow mast of round, square or rectangular section made up of long strips of wood.

Breasthook - Timber knees placed horizontally between two fore ends of stringers to reinforce their connection to the stem.

Butt Block - A short longitudinal piece of wood used to back up the connection of two plank ends.

Buttock - That part of a vessel's stern above her waterline which overhangs or lies abreast of the stern post; the counter.

Buttock Lines - Lines representing fore and aft vertical sections from the centerline outward.

Charlie

Camber - The curve of a deck athwartships.

Cant Frames - Frames whose plane of support is not perpendicular to the fore and aft line.

Capping - Fore and aft finished piece along the topside of an open boat, often improperly termed gunwale; called a covering board, margin plank or plank sheer in a decked vessel.

Carlin - The fore and aft members of the deck framing system.

Carvel Planked - Smooth skinned planking whose strakes run fore and aft.

Caulking (calking) - Cotton, oakum or other fiber driven into planking seams to make them watertight.

Ceiling - An inner skin of the hull often used to add strength in boats having sawn frames. In some cases the ceiling is not structural but merely serves to line the hull for decorative purposes or for ease in cleaning. 

Chain Plate - (Shroud Plate) A flat strip of metal fastened through the hull, either from inside or outside, to which the lower ends of the shrouds are attached.

Check - A lengthwise separation of the wood that usually extends across the rings of annual growth and commonly results from stresses set up in wood during seasoning.

Chine - The line of intersection of the bottom with the side of a vee or flat bottomed vessel.

Clamp - The fore and aft member at the sheer line of the vessel to which the deck beams usually fasten.

Clench Planking - Lapstrake, in which the adjacent planks overlap like clapboards of a house.

Clench Fastening - Securing a nail or rivet by placing a rove (washer) over the inboard side and then bending the fastening over it. In many cases they are simply bent over by driving them against a backing iron, causing them to reenter the frame.

Clinker Built - See clench planking.

Coat (Mast) - A protective piece, usually canvas, covering the mast wedges where the mast enters the deck.

Cold Bent (frames) - Frames which are bent on forms and after shaping are fitted to the vessel.

Cold Molded - A method of boat construction using a male mold over which layers of thin wood and/or plywood are diagonally laid and glued together. Can be covered with epoxy or FRP.

Cove Line - A hollowed out decorative line found along the sheer of a boat.

Covering Board - A plank used as a "washboard" or "plank sheer" along the outer edge of the deck. - See Capping.

Cutwater - The forward edge of the stem at the waterline.

Delta

Dead Rise - The amount the bottom rises from keel to chine - most properly applied to "Vee" bottom construction but also used in reference to the rising bottom of round bottom boats.

Deadeye - A stout disk of hard wood, strapped with rope or iron, through which holes (usually three) are pierced for the reception of lanyards. They are used as blocks to connect shrouds and chain plates.

Deadwood - The vertical structure built up from the keel to support the cant frames at the stern or stem; longitudinal timbers of a vessel's structural backbone which lie entirely outside the keel, sternpost, and horn timber rabbett lines.

Decay - The decomposition of wood substance by fungi.

1. (Advanced or typical) - The older stage of decay in which the destruction is readily recognized because the wood has become punky, soft and spongy, stringy, ringshaked, pitted or crumbly. Decisive discoloration or bleaching of the rotted wood is often apparent.

2. (Incipient) - The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood. It is usually accompanied by a slight discoloration or bleaching of the wood.

Deck Head - The underside of the deck.

Diagonal Planking - Planking laid on an angle to the keel.

Displacement - The actual weight of a boat as it "displaces" its weight when afloat; not to be confused with admeasurement tonnages.

Drift (Pins, Bolts) - A long fastening driven (pin) or threaded (bolt) to receive end nuts, used for joining heavy timbers such as horn timbers and stern frames; also used to fasten and reinforce wooden panels on edge, such as rudders and centerboard trunks.

Dry Rot - A term loosely applied to any dry, crumbly rot but especially to that which, when in an advanced stage, permits the wood to be crushed easily to a dry powder. The term is actually a misnomer for any decay, since all fungi require over 20% moisture to grow.

Dutchman - Wooden block or wedge used to fill the void in a badly made butt or joint; a graving piece or repairing patch in a deck; filler; shim; short plank.

Echo

Edge-Grained Lumber - Lumber that has been sawn so the wide surfaces extend approximately at right angles to the annual growth rings. Lumber is considered edged grained when the rings form an angle of 45 degrees to 90 degrees with the wide surface of the piece.

Edging - Amount required to be cut away from the edge of a plank in fitting strakes.

Edge Nailed - A method of fastening a strip plank to adjacent planks.

Foxtrot

Facing - Building one piece of timber on another for strength or finish purposes.

False Keel - Sacrificial batten added to the keel to protect the keel from grounding and from marine borers; eg. worm shoe.

Faying - Joining closely together.

Flat-Grained Lumber - Lumber that has been sawed in a plane approximately perpendicular to a radius of the log. Lumber is considered flat grained when the annual growth rings make an angle of less than 45 degrees with the surface of the piece.

Floor or Floor Timber - A transverse structural member lying across the keel and tying the frames on either side of the keel together. The central futtock or futtocks of a sawn frame, lying across the
keel. Floor timbers join both sides of a vessel together and make up the substructure for external keel fastenings, engine beds, and mast steps.

Floorboards - Planking laid on top of the floors to provide a walkway. Also known as the "sole."

Frame - The transverse structure at each section giving form to the hull. Frames connect to the keel or keels on and to the clamp or shelf at the sheer. Also known as "ribs."

Freeing Port - Any direct opening through the vessel's bulwark or hull to quickly drain overboard water that has been shipped on exposed decks.

Futtock - Curved parts or sections of transverse frames extending from the floor timbers to the top timbers.

Golf

Garboard - The strake of planking nearest the keel.

Green - Freshly sawed lumber, or lumber that has received no intentional drying; unseasoned. The term does not apply to lumber that may have become completely wet through waterlogging.

Grub Beam - A built up beam of short heavy timbers used to shape a round stern.

Gusset - Any piece that is used to join or strengthen the joint of two other pieces.  

Hotel

Hanging Knee - A strengthening bracket used between frames and deck beams.

Heartwood - The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood may be infiltrated with gums, resins, and other materials that usually make it darker and more decay resistant than sapwood.

Horn Timber - One or more timbers forming the main support for an overhanging stern and extending aft from the upper end of the stern post. Also used for timber connecting the shaft log and body post with the rudder post.

Horse (n) - The form upon which a small boat is built.

Horse (v) - To drive home, as to horse caulking.

Hot Frame - A frame which, after being softened by heat, is bent into shape as it is installed.

India

Juliett

Joint - The junction of two pieces of wood or veneer.

Butt Joint - An end joint formed by abutting the squared ends of two pieces. Because of the inadequacy in strength of butt joints when glued, they are not generally used.

Edge Joint - The place where two pieces of wood are joined together edge to edge, commonly by gluing. The joints may be made by gluing two squared edges as in a plain edge joint or by using machined joints of various kinds, such as tongue-and-grooved joints.

End Joint - The place where two pieces of wood are joined together end to end, commonly by scarfing and gluing.

Lap Joint - A joint made by placing one piece partly over another and bonding the overlapped portions.

Scarf Joint - An end joint formed by joining with glue and mechanical fastenings the ends of two pieces that have been tapered or beveled to form a sloping plane surface, to the same length in both pieces. In some cases, a step or hook may be machined into the scarf to facilitate alignment of the two ends, in which case, the plane is discontinuous and the joint is known as a stepped or hooked scarf joint or scarf joint with nib.

Starved Joint - A glued joint that is poorly bonded because insufficient quantity of glue remained in the joint. Starved joints are caused by the use of excessive pressure or insufficient viscosity of the glue, or a combination of these, which result in the glue being forced out from between the surfaces to be joined. This term should only apply to epoxy glues. Joints made with other waterproof or water resistant glues like resorcinol and urea-formaldehyde (brown glue) should be starved for maximum strength.

Kilo

Keelson - An inner keel usually laid over the floors and through bolted to the keel.

Kerf, Kerfing - To cut or make a channel with a saw blade.

Kiln Dried - As in timber, refers to forced hot air circulation through a chamber to dry the wood.

King Plank - The centerline plank of a deck.

Knee - See Hanging Knee.

Knot - That portion of a branch or limb which has been surrounded by subsequent growth of the wood of the trunk or other portion of the tree. As a knot appears on the sawed surface, it is merely a section of the entire knot, its shape depending upon the direction of the cut.

Lima

Lapstrake - See Clench Planking.

Limber - A hole allowing the free passage of water from one area to another.

Lignum Vitae - A hardwood used for deadeyes and propeller shaft bearings.

Mike

Making Iron - A large caulking iron used to drive oakum into plank seams.

Mast Partners - Carlins between deck beams to strengthen the area where the mast passes through the deck.

Molding - Measurement of a plank or timber from inboard to outboard, i.e., parallel to the plane in which the member lies; opposed to siding measured at right angles to such plane. Thus, the molding of a frame is measured in the thwartship direction while that of a stern piece is its cross sectional dimension fore and aft.

November

Nib - The squared off end of a tapered piece such as a scarf.

Noble Metal - A metal most resistant to deterioration due to galvanic action; the cathodic material.

Oscar

Oakum - A caulking material of tarred fibers.

Papa

Partner - Stiffening or supporting pieces fitted in way of the passage of a mast through a deck. See Mast Partners.

Paying - The filling of the seam with seam putty, pitch, tar, or other type of seam sealant after caulking it.

Pitch Pocket - An opening extending parallel to the annual growth rings containing, or that has contained, pitch, either solid or liquid.

Plank - Strips of wood that form the "skin" of a boat; strakes.

Plank Sheer - See Capping.

Preservative - Any substance that for a reasonable length of time is effective in preventing the development and action of wood-rotting fungi; borers of various kinds and harmful insects that deteriorate wood.

Prick Post - An outer post supporting an outboard rudder.

Quebec

Quarter Knees - Lateral brackets similar to the breast hook used to join the sheer shelf or clamps to the transom.

Quartersawed Lumber - Another term for Edge-Grained Lumber.

Romeo

Rabbet - A longitudinal channel or groove in a member which received another piece to make a joint.

Racking - Two or more structural members working and becoming loose; structural deformation of the transverse section of a ship's hull. A vessel is said to be racked if, when viewed end on, it appears to be leaning or tilting over to one side. Symptoms of racking generally appear at the junction of the frames with the beams and floors.

Resorcinol - A formaldehyde resin to which a powder hardener is added to form a strong water resistant wood glue.

Rib - See Frame.

Sierra

Sampson Post - Any post well attached to the vessels structure to take excessive loads; used as a bitt.

Scantling - The dimensions of all structural parts used in building a boat. A full scantling vessel is of maximum required structural dimensions.

Scarf (scarph) (n) - A joint by which the ends of two structural pieces of timber are united so as to form a continuous piece; a lapped joint made by beveling off, notching or otherwise cutting away the sides of two timbers at ends, and bolting, riveting, or strapping them together so as to form one continuous piece without increase in sectional area at the joint.

Scarf (v) - To join the ends of two timbers so as to form a continuous piece in appearance; the joining of wood by sloping off the edges and maintaining the same cross section throughout the joint.

Scupper - A pipe or tube leading down from a deck and through the hull to drain water overboard.

Shake - A separation along the grain, the greater part of which occurs between the rings of annual growth.

Sheer, Sheer Line - The intersection of the deck and the hull; the longitudinal sweep of the deckline from the stem to the sternpost upward at the ends in traditional designs, and downwards at the ends in reverse-sheer designs.

Sheer Strake - The top or uppermost plank in a hull.

Shelf - Line of timbers bridging and thus stiffening frames but chiefly for supporting the end of the deck beams.

Shipworm - A misnomer for the wood boring mollusk Teredo which feeds on wood cellulose. Another but different marine borer, the Limnorae, is also misnamed shipworm.

Siding - Generally the sawn or planed thickness of the planks or timbers from which wood members are shaped or cut. See Molding.

Sister - As in sister frame or sister keelson. A member attached to or laid alongside an original member to strengthen it, either as an original construction technique or as a repair.

Spiling - The edge curve in a strake of planking.

Split - A separation of the wood with the grain due to the tearing apart of the wood cells.

Spline - As in spline planking. A thin tapered strip of wood glued and hammered into carvel plank seams which have become enlarged and spill caulking internally.

Stain - A discoloration in wood that may be caused by such diverse agencies as micro-organisms, metal, or chemicals. The term also applies to materials used to impart color in wood.

Stealer - In the shell planking toward the ends of a vessel a strake introduced as a single continuation of two tapering strakes. One of (usually the shorter or narrower of) the two planks which are butted into a single plank as double continuation or as the short piece notched into a larger plank to add width not available on one board.

Stern Frame - The frame work around the inside of the transom.

Stopwater - A softwood dowel driven across a lap, scarf, or butt joint in the backbone structure or elsewhere, to prevent seepage of water into the hull; any contrivance to accomplish this purpose.

Strake - One of the rows or strips of planking constituting the surface of the hull.

Strip Planking - Carvel construction where each plank is edge nailed to the adjacent planks.

Tango

Taffrail - A timber rail around the aft deck of a vessel.

Treenail - (Trunnel) A wood dowel used as a fastening; often fitted with a wedge in the dowel end to hold it in place. Dense wood such as locust is used for the dowel.

Uniform

Victor

Whiskey

Wane - A defective edge or corner of a board caused by remaining bark or a beveled end.

Warp - Any variation from a true or plane surface. Warp includes bow, crook, cup and twist or any combination thereof.

Weathering - The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, action of dust and sand carried by winds and alternate shrinking and swelling of the surface fibers with the variation in moisture content brought by changes in the weather. Weathering does not include decay.

Welt - A strip of wood fastened over a flush joint or seam for strengthening purposes; a seam batten.

Wicking - A caulking material such as oakum or cotton , used to wrap a fastening in order to protect it from moisture.

Worm Shoe - A non-structural piece of wood placed at the bottom of the keel to protect the keel from marine borers.

Xray

Yankee

Zebra